小编dra*_*ust的帖子

我有Viewpager机智2片段:CurrentWeatherFragment和ForecastFragment.我需要将字符串从一个传递到另一个,Iam使用如下所示的界面,但我一直得到NullPointerException,消息没有通过属性...

public class CurrentWeatherFragment extends Fragment {

SendMessage SM

public void onCreateView(...) {
String Message = "Hello"
SM.sendData(Message);
}

interface SendMessage
{
    public  void sendData(String message);
}

@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);

    try {
        SM = (SendMessage) activity;
    } catch(ClassCastException e) {
        throw  new ClassCastException("Musisz zaimplementowac metode sendData");
    }
}
}

MainActivity.java

import android.support.v4.app.FragmentActivity;
import android.support.v4.view.ViewPager;
import android.os.Bundle;


public class MainActivity extends FragmentActivity implements CurrentWeatherFragment.SendMessage {

ViewPager viewPager;


@Override
protected void onCreate(Bundle …